Skirting system for surface effect machine

ABSTRACT

A multilobed flexible skirt device for a surface effect machine, comprising a flexible diaphragm, such as a canvas, connecting the lobes of the skirt, the diaphragm being only partly continuous, since it is cut away over a predetermined curve, and being attached on the one hand to the skirt at the cuspidal edge junctions of its lobes and on the other hand to the skirt support structure of the machine.

United States Patent lnventor Appl. No.

Filed Patented Assignee v Priority Guy Robert Delamare llerblay, France May 13, 1968 Feb. 9, 1971 Societe DEtudes Et De Developpement Des Aeroglisseurs Marins S.E.D.A.M. Paris, France a company of France May 18, 1967 France SKIRTING SYSTEM FOR SURFACE EFFECT MACHINE 3 Claims, 10 Drawing Figs.

Int. Cl B60v H16 [50] Field of Search 180/127,

[56] References Cited UNITED STATES PATENTS 3,414,075 12/1968 Bertin 180/121 3,416,627 12/1968 Francis et a1. 180/127 Primary Examiner--A. Harry Levy Attorney-Stevens, Davis, Miller & Mosher ABSTRACT: A multilobed flexible skirt device for a surface effect machine, comprising a flexible diaphragm, such as a canvas, connecting the lobes of the skirt, the diaphragm being only partly continuous, since it is cut away over a predetermined curve, and being attached on. the one hand to the skirt at the cuspidal edge junctions of its lobes and on the other hand to the skirt support structure of the machine.

PATENTEUFEB slam 3561 559 SHEET 1 0r 4 PATENTEDFEB' slam 3.561.559

SHEET u 0F 4 I Fig-'8 4 7 B 23 SKIRTING SYSTEM FOR SURFACE EFFECT MACHINE The present invention relates to improvements to the flexible skirt devices used for bounding pressurized fluid cushions in ground-effect machines, more particularly the lobated or multilobed skirts, an embodiment of which is illustrated in FIG. 6 of U5. Pat. No. 3,346,063.

One of the objects of the invention is to provide a means of retaining a flexible skirt of the kind specified. Other objects of the invention are to counteract to some extent the natural tendency of flexible skirts to assume a circular shape as a result of the internal pressure exerted on the skirts, and to give the skirts a shape which causes only low aerodynamic and hydrodynamic drag, and also to make the skirts more readily fittable to the structure of the machine.

Another object of the invention is to ensure that the internal stresses are uniformly distributed throughout the material of the skirt.

In the case of a peripheral skirt enclosing a plurality of internal elementary cushions (another embodiment disclosed in the aforementioned patent), the present invention obviates the folds in the peripheral skirt, gives it a greater flexibility, and brings the internal elementary cushions closer to one another.

It has already been suggested to stabilize the lobes of a mu]- tilobed skirt by cables or chains connected to the skirt support, or by continuous or solid partitions. However, embodiments of this kind either cause high local concentrations of stresses in the skirt, leading to breakages of the canvas, or produce prohibitive conditions of weight.

The present invention applies the principle of the so-called suspended bridge, to ensure that at the place where the skirt is lobed, forces are distributed uniformly by a parabolic definition, thus reducing strains and risks of breakages.

According to the present invention, the lobes of a multilobed flexible skirt are connected by a diaphragm, such as a canvas, which is only partly continuous, since it is cut away over a predetermined curve, and which is attached on the one hand to the skirt at the cuspidal edge junction of its lobes, and on the other hand to the skirt support.

In one embodiment of the invention, the diaphragm is cut away over a single or multiple parabolic curve extending between two points of attachment to the support. As avariant, the curve can take a catenary form.

In the accompanying drawings:

FIG. 1 is a diagrammatic perspective view of a two-lobe skirt having a cutaway diaphragm according to the present invention;

FIGS. 2-4 are diagrams showing different shapesin which the diaphragm may be cutaway;

FIG. 5 is a diagrammatic perspective view of a multilobe and multidiaphragm skirt;

FIG. 6 shows an adaptation of the diaphragm to a machine of the peripheral fluid curtain type;

FIG. 7 illustrates an arrangement of the fetaining diaphragms of a multilobed peripheral skirt;

FIG. 8 is a diagrammatic vertical half-section showing a variant method of attachment; and

FIGS. 9 and 10 illustrate another variant embodiment.

FIG. 1 shows a flexible skirt 1 laterally boundinga pressurized fluid cushion and having two frustoconical lobes 2, 3 which, viewed in plan, take the form of incomplete circles joined in a plane of intersection which will in general be perpendicular to the extension of the free edge of the skirts and which comprises an axis A-A extending through the chord of intersection, and a central axis B-B substantially perpendicular to the axis A-A, the third axis C-C being parallel to the central longitudinal plane of the ground-effect machine, for instance an air-cushion vehicle.

According to the present invention, the skirt 1 is retained by means of a canvas or diaphragm 4 cut away over an outline 5 to be defined hereinafter. The partly continuous diaphragm is rigidly connected to the skirt 1 along two generatrices or cuspidal edges 6, 6, at the intersection of the lobes 2, 3. The diaphragm is attached to the support (not shown), which can be the platform of the vehicle, at two upper points 7, 7 disposed on the transverse axis A-A, and at a lower point 8 disposed on the axis B-B.

FIG. 2 is a partial section, taken along the transverse plane AABB of FIG. 1. and shows more clearly the shape of the cutaway portion 5 of the diaphragm 4. In this embodiment. in which the skirt 1 has two frustoconical lobes 2, 3, the curve takes the form of a parabola having an axis X-X and its apex at the point 9. However, with different operation of the pressure inside the cushion, different shape of the skirt, etc., the point 9 can be brought to a place III on the edge 6, as shown in FIG. 3, the internal edge 5 of the diaphragm 4 still maintaining a parabolic outline. In the variant shown in FIG. 4, the internal edge 5 can take a catenary shape.

FIG. 5 shows the application of retaining diaphragms 4 to a skirt 11 having six lobes; the skirt can either be an internal elementary skirt, or a peripheral enveloping skirt. Since the assembly is symmetrical about the axis 8-3, the lower point 8 of attachment will be shared by the three diaphragms 4, while three pairs of upper points 7, 7 of attachment will be provided.

The retaining diaphragm according to the invention is applicable not only to cushions of the so-called plenum chamber type, as described hereinbefore, but also to cushions of the peripheral fluid curtain type. FIG. 6 illustrates an application of this kind. The nozzle 13 for forming the fluid curtain 12 is shown between the inner 14 and outer 15 edges of the peripheral curtain; the edges 14, 15 can be connected by tie rods or cables 16, 16, or by a suitably profiled radial struttingcanvas.

FIG. 7 shows a preferred embodiment of the invention, applied to a multilobed skirt enclosing; a plurality of downwardly tapering frustoconical internal elementary skirts J aligned in two rows parallel with the longitudinal axis C-C on either side thereof.

In the embodiment illustrated, three dihedrally-paired retaining diaphragms 4 are provided; the paired canvasses of one diaphragm are not in the continuation of one another, but at a certain relative inclination, as can be clearly seen in FIG. 7, cables or tie rods 18 ensuring that the relative inclination is maintained.

FIG. 7 again shows the upper points 7, 7 of attachment shown in FIG. 1, but the lower attachment is now at two points 19a, 19b which could be disposed in the central longitudinal plane B-BC-C, but are in fact at a distance therefrom.

FIG. 8 clearly illustrates an arrangement of this kind. It can be seen that points l9a l9b of attachment are connected via tie rods 20, 21 to the axis 8-8 by the agency of any suitable mechanism. FIG. 8 shows a conical member 22 attached to the floor 23 of the apparatus. This conical member 22 acts as a hanging attachment to a first clevislike connecting member 24 from which a connection 25 terminating in a ring 26 is suspended. In all cases, the outline 5a, 5b is parabolic.

The required parabolic outline can be determined by means of a steel or glass wire or cable 27 (cf. FIGS. 9 and 10) tensioned by the canvas diaphragm 4 and transmitting the forces to attachments 7, 8. The canvas diaphragm 4 must adhere to the wires 27 so that it can be loaded. thereby; this can be done by the interposition of a moulded channel 28 which adheres both to the diaphragm 4 and the wire 27.

Iclaim:

1. A surface effect machine movable above a generally horizontal bearing surface and having a longitudinal medial plane orthogonal to said bearing surface, said machine comprising a support structure spaced above said bearing surface and generally parallel thereto, and a lobated flexible skirting device depending from said structure and including an outer skirt defining juxtaposed lobes joined along cuspidal edges, and an inner diaphragm means interconnecting said cuspidal edges and attached thereto, said diaphragm means being only partly solid and having a cutout portion of curved outline, wherein the improvement comprises: means for attaching said diaphragm means to said support structure at two spaced upper points of said diaphragm means lying on a straight line substantially perpendicular to said longitudinal medial plane, and further means for attaching said diaphragm means to said support structure at two tiered points of said diaphragm means, both lying intermediate to and at a lower level than said two upper points, said further means comprising an attachment member secured to said support structure and positioned in said longitudinal medial plane in spaced relation with said two tiered points, a first tie extending between the uppermost one of said two tiered points and said attachment member, a spacer member depending from said attachment member and having a lower end, and a second tie extending between the lowermost one of said two tiered points and said lower end of said spacer member.

2. Machine as claimed in claim I, wherein said diaphragm means has a cutout portion of curved outline composed of two arcuate sections interconnected at a point of inflection which is said uppermost one of said two tiered points and which is attached to said first tie.

3. A surface effect machine movable above a generally horizontal bearing surface and having a longitudinal medial plane orthogonal to said bearing surface. said machine comprising a support structure spaced above said bearing surface and generally parallel thereto, and a lobated flexible skirting device depending from said structure and including an outer skirt defining juxtaposed lobes joined along cuspidal edges, and an inner diaphragm means interconnecting said cuspidal edges and attached thereto, said diaphragm means being only partly solid and having a cutout portion of curved outline, wherein the improvement comprises: means for attaching said diaphragm means to said support structure at two spaced upper points of said diaphragm means lying on a straight line substantially perpendicular to said longitudinal medial plane. and further means for attaching said diaphragm means to said support structure at a third point of said diaphragm means lying intermediate to and at a lower level than said two upper points, said third point being spaced from a transverse plane through said straight line and orthogonal to said longitudinal medial plane, and said diaphragm means being of dihedral shape. 

1. A surface effect machine movable above a generally horizontal bearing surface and having a longitudinal medial plane orthogonal to said bearing surface, said machine comprising a support structure spaced above said bearing surface and generally parallel thereto, and a lobated flexible skirting device depending from said structure and including an outer skirt defining juxtaposed lobes joined along cuspidal edges, and an inner diaphragm means interconnecting said cuspidal edges and attached thereto, said diaphragm means being only partly solid and having a cutout portion of curved outline, wherein the improvement comprises: means for attaching said diaphragm means to said support structure at two spaced upper points of said diaphragm means lying on a straight line substantially perpendicular to said longitudinal medial plane, and further means for attaching said diaphragm means to said support structure at two tiered points of said diaphragm means, both lying intermediate to and at a lower level than said two upper points, said further means comprising an attachment member secured to said support structure and positioned in said longitudinal medial plane in spaced relation with said two tiered points, a first tie extending between the uppermost one of said two tiered points and said attachment member, a spacer member depending from said attachment member and having a lower end, and a second tie extending between the lowermost one of said two tiered points and said lower end of said spacer member.
 2. Machine as claimed in claim 1, wherein said diaphragm means has a cutout portion of curved outline composed of two arcuate sections interconnected at a point of inflection which is said uppermost one of said two tiered points and which is attached to said first tie.
 3. A surface effect machine movable above a generally horizontal bearing surface and having a longitudinal medial plane orthogonal to said bearing surface, said machine comprising a support structure spaced above said bearing surface and generally parallel thereto, and a lobated flexible skirting device depending from said structure and including an outer skirt defining juxtaposed lobes joined along cuspidal edges, and an inner diaphragm means interconnecting said cuspidal edges and attached thereto, said diaphragm means being only partly solid and having a cutout portion of curved outline, wherein the improvement comprises: means for attaching said diaphragm means to said support structure at two spaced upper points of said diaphragm means lying on a straight line substantially perpendicular to said longitudinal medial plane, and further means for attaching said diaphragm means to said support structure at a third point of said diaphragm means lying intermediate to and at a lower level than said two upper points, said third point being spaced from a transverse plane through said straight line and orthogonal to said longitudinal medial plane, and said diaphragm means being of dihedral shape. 